Pulse Waveform Analysis of the Ocular Blood Flow Using Laser Speckle Flowgraphy before and after Glaucoma Treatment

Abstract

Although reduction in intraocular pressure (IOP) is the principle of glaucoma treatment, impaired ocular blood flow is believed to play a role in the progression of glaucoma. This study evaluated the effect of glaucoma treatment on pulse waveforms for optic nerve head (ONH) microcirculation in patients with glaucoma. Fifty-one subjects were included on the basis of the glaucoma treatment administered, which involved instillation of prostaglandin (PG) analogs (PG group; n = 28) or trabeculectomy (trabeculectomy group; n = 23). ONH blood flow, represented by the mean blur rate (MBRT) and pulse waveforms, was measured using laser speckle flowgraphy before and 1 and 3 months after treatment. Three months after treatment, IOP exhibited a significant decrease (p < 0.05). Although there was no significant change in MBRT after treatment, the acceleration time index (ATI) significantly decreased (p=0.034) in the PG group. In the trabeculectomy group, there was no significant change in the MBRT after treatment, while fluctuation (p=0.019) and blowout score (BOS) (p=0.036) exhibited significant decrease and increase, respectively. Multiple regression analysis showed that mean deviation was significantly associated with the rate of change in the BOS (p=0.013), age was a significant contributing factor for the rate of change in fluctuation in the trabeculectomy group, reflection was significantly associated with the ATI (p=0.037) in the in the PG group. Both glaucoma treatments can change the pulse waveforms, with MBRT remaining unchanged, and IOP reduction owing to the treatment may contribute to stable blood flow in the tissue area of the ONH. As impaired ocular blood flow plays a role in the progression of glaucomatous damage, it would be beneficial if glaucoma treatment could improve the stability of ONH microcirculation.

Characterization of laser speckle flowgraphy pulse waveform parameters for the evaluation of the optic nerve head and retinal circulation

“…Conversely, LSFG pulse waveforms themselves are relatively free from such effects; therefore, they could be more suited for inter-individual comparison of the ONH or retinal circulatory status than the MT or MV. Several LSFG pulse waveform parameters reportedly showed significant differences between normal and glaucoma eyes 24 – 26 , between various disease stages of glaucoma 24 , and a significant change after trabeculectomy 27 , 28 , and water drinking 29 . Further, a significant correlation of leukocyte glutathione levels, an indicator of mitochondrial dysfunction, was found with one LSFG pulse waveform parameter for MT in glaucoma patients 30 .…”

Changes in Pulse Waveforms in Response to Intraocular Pressure Elevation Determined by Laser Speckle Flowgraphy in Healthy Subjects

“…Eyes with poor autoregulation are at much greater risk of developing ONH ischemic damage than those with e cient autoregulation. Thus, under the abnormal conditions in which autoregulation of the blood ow is lost, such as in eyes with diabetic retinopathy [40] and with glaucoma [41], it is important to pay more attention to the increase in the IOP in such diseases.…”

Sex differences in the association between systemic oxidative stress status and optic nerve head blood flow in normal-tension glaucoma

“…BOS-T is an indicator of the volume of blood flow maintained in a vessel between heartbeats [26]. BOT-T is defined as the ratio of the half width (i.e., the time that the waveform is higher than half of the mean of the minimum and maximum signals) in one heartbeat [27,28]. All statistical analyses of ONH blood flow were based on an average of three separate LSFG measurements.…”